The fuel necessary to operate boilers, heating furnaces, melting furnaces and other burning apparatus under today's circumstances, tends to rise in price and lower in quality, making it desirable, therefore, to save energy and to prevent the effects of pollution. For this purpose, the fuel should burn well, that is, be low in the contents of O.sub.2, soot and NO.sub.x. It is known that these functions depend usually on the spraying characteristics of the fuel and its mixing characteristics with air.
In the conventional burning apparatus, not only is fuel used, but also a spraying medium such as air or steam is used to propel the fuel in a jet into the burner. When the spraying medium is jetted out of a nozzle, that is, jetted from the high pressure side to the low pressure side, it will mix with and finely granulate the fuel by the energy of the expanding spray.
However, since liquid fuel is an imcompressible fluid and has little dispersibility in itself, it is necessary to increase the degree of mixing of the spraying medium with it in order to promote the fine granulation of the liquid fuel. Generally, the amount of mixing of the spraying medium must be increased. Thus, this has been a defect in that any saving of fuel energy is lost in the mixing.
Further, particles in the spray fluctuate so much in their granularity as to be different in the rate of mixing with air for combustion and a favorable combustion is hard to attain. Therefore, the modification of the wind box and blower around the conventional burner has been costly.
Further, in order to attain low NO.sub.x, apparatus has been proposed for slow combustion (such as exhaust gas recirculation, two-step combustion or divided flame combustion), water injection (reduction of efficiency by the evaporation of the latent heat of water) or de-nitrification. These steps also have the defect that the saving of energy is lost.
The burner tip of the present invention is made to eliminate such defects as are mentioned above. It changes the jet manner, promotes the mixing of a liquid fuel with such spraying medium as air or steam and produces the fine granulation of the liquid fuel and enables the combustion to be effective and economical to thereby save energy and prevent pollution.